Leviticus 27:31-33

New Revised Standard Version Catholic Edition

³¹ If persons wish to redeem any of their tithes, they must add one-fifth to them. ³² All tithes of herd and flock, every tenth one that passes under the shepherd’s staff, shall be holy to the Lord. ³³ Let no one inquire whether it is good or bad, or make substitution for it; if one makes substitution for it, then both it and the substitute shall be holy and cannot be redeemed.